Hydraulically actuated diaphragm pump



Jan. 29, 1963 P. J. EIFEL HYDRAULICALLY ACTUATED DIAPHRAGM PUMP 2 Sheets-Sheet 1 Filed April 6, 1960 mam Mmww w J M a Y ...w an a j w w w J em. 0 Wm Z w w 4 a Z; 4 m2 2 0% u v Q I United States Patent 3,tl'75,468 HYDRAULICALLY ACTUATED DIAPHRAGM PUMP Paul J. Eii'el, Chicago, Ell, assignor to Hills-McCanna Company, Chicago, Ill., a corporation of Hlinois Filed Apr. 6, less, er. No. 20,462 2 Claims. (Q1. 103-44) The present invention relates to diaphragm pumps in which the pumping diaphragms are actuated hydraulically in a manner such that the pressure on the diaphragms of the fluid being pumped is opposed by the pressure of hydraulic actuating fluid on the diaphragrns. Diaphragm pumps, particularly hydraulically actuated pumps, can be used to great advantage in pumping fluids which must not be allowed to escape to the external environment even in small quantities.

A diaphragm pump is inherently susceptible of being completely sealed against the escape of the fluid being pumped as long as the diaphragm remains unbroken and impervious to the fluid. However, purely mechanical actuation of a pump diaphragm tends to create stresses in the diaphragm which can cause it to fail prematurely in service, particularly when pumping fluid under high pressure. Stresses on a pumping diaphragm caused by the pressure of the fluid being pumped can be greatly minimized by actuating the diaphragm hydraulically in a manner such that the hydrostatic pressure of the hy draulic actuating fluid opposes the pressure force on the diaphragm of the fluid being pumped.

However, the actuation of a pump diaphragm by hydraulic fluid presents a number of challenging problems, which are the particular concern of the present invention.

()ne object of the invention is to provide a hydraulically actuated diaphragm pump having a new and improved construction and mode of operation which assures maintenance of maximum operating efliciency and output capacity of the pump at all times, while at the same time avoiding the application of excessive hydrostatic pressure to the pumping diaphragm.

Another object is to provide a hydraulic-ally actuated I diaphragm pump of improved construction which functions automatically as an incident to energization of the pump to fill hydraulic actuating space within the pump with an optimum quantity of diaphragm actuating fluid and to completely free the hydraulic actuating space of entrapped air.

Another object is to provide an improved, hydraulically actuated diaphragm pump which is so constructed that an optimum volume of actuating liquid is maintained in hydraulic actuating space in the pump, even though liquid may be lost from this space through leakage or otherwise, by operation of an air-liquid discriminating valve of simple, trouble free construction which serves to release and replace with an optimum quantity of liquid any air or other gas which for any reason may have been entrapped in the hydraulic actuating space.

A further object is to provide an improved diaphragm pump as recited in the preceding objects in which new and improved pump structure provides for efficient operation of the air-liquid discriminating valve, while at the same time obviating any necessity for interconnecting this valve with other working parts of the pump.

Another object is to provide a hydraulically actuated diaphragm pump having a new and improved construction which provides for eflicient high speed operation of the pump, while at the same time serving to admit supplementary quantities of hydraulic fluid into the hy draulic actuating space within the pump only as necessary to maintain an optimum quantity of fluid in the actuating space and in a manner which substantially avoids any I 3,75,4ifi8 Patented Jan. 2a, 1953 reduction in the pressure within the actuating space below ambient pressure conditions.

An additional object is to provide an improved diaphragm pump as recited in the previous objects in which reductions in the pressure Within the hydraulic actuating space below atmospheric pressure conditions are avoided and optimum supplementary quantities of hydraulic fluid are added to the hydraulic actuating space by the operation of a simple reliable valve which operates independently of mechanical connections to other working parts of the pump.

A further object is to provide an improved hydraulically actuated pump as recited in the foregoing objects in which the diaphragm is supported and protected against excessive hydrostatic actuating pressure in a manner which obviates subjecting the diaphragm to damaging stresses.

Other objects and advantages will become apparent from the following description of the exemplary form of the invention illustrated in the drawings, in which:

FIGURE 1 is a perspective view of a pump embodying the invention;

FIG. 2 is a fragmentary, horizontal sectional view of the pump taken along the plane indicated by the line 22 in FIG. 1;

FIG. 3 is a fragmentary sectional view on a greatly enlarged scale showing the air-liquid discriminating valve incorporated in the pump and appearing in FIG. 2;

FIG. 4 is a fragmentary sectional view of the structure appearing in the central portion of FIG. 3, but showing the valve in closed rather than open position;

FIG. 5 is a horizontal sectional view taken along the line 5-5 of FIG. 3;

FIG. 6 is a fragmentary sectional view on a greatly enlarged scale taken along the line 6-6 of FIG. 3;

FIG. 7 is an exploded perspective view of the airliquid discriminating valve used in the pump; and

FIG. 8 is a fragmentary sectional view showing the pump diaphragm upon completion of a discharge stroke.

The diaphragm pump 10 forming the exemplary embodiment of the invention illustrated comprises a pump body 12, mounted as shown in FIG. 1, on one end of a frame 14 that houses a power driving mechanism 16 of generally conventional construction, which reciprocates a pump actuating plunger 18. The plunger 18 extends through a sealing sleeve 20 into a horizontfl bore 22 in the housing 12. The bore 22 is made somewhat larger in diameter than the plunger 18, thus avoiding frictional engagement of the plunnger with the bore. A high pressure seal 24 supported within the sleeve 29 in encircling relation to the plunger 18 is designed to prevent fluid from escaping from the bore 22 around the plunger.

Reciprocation of the plunger 18 is used to effect bydraulic actuation of a pumping diaphragm 26, as will presently appear.

The diaphragm has a circular shape and is formed of a tough, flexible material. The circumferential marginal edge of the diaphragm is tightly clamped between two sections 2%, 30, of the housing 12, which are connected together by screw elements 32, FIGS. 1 and 2. The two housing sections 28 and 30 are formed by metal castings which clamp the diaphragm with suflicient force to preclude the escape of fluid around the clamped periphery of the diaphragm.

Thus supported, the diaphragm 26 extends across a circular cavity 34 formed by two complementary circular recesses 36, 38 defined in the opposed housing sections 28 and fill in facing relation to each other, as shown in FIG. 2. The cavity 34 thus formed is partitioned by the diaphragm 26 to define a pumping chamber 40 and a hydraulic actuating chamber 42 which are alternately conarie nd. xpandsdb a tua q of h ia hr m, will presently appear.

The pumping chamber 40 is connected through a bore 44 with inlet and outlet check valves 46, 48. As shown, two inlet valves 46 are used in tandem to connect the bored- 4 with an intake line 59, and two outlet check valves 48 are used to connect the bore 44 with a discharge line 52.

Movement of the diaphragm 26 to expand and contract the pumping chamber 40 produces a pumping action which forces fluid from the intake line 50 into the dischange line 52.

As previouslyintimated, diaphragm pumps of this character have special advantages in pumping corrosive chemicals and other fluids which can not be allowed to escape even in small quantites. The space within the pump, including the pump chamber 40, is completely sealed against the escape of fluid as long as. the diaphragm 26 remains intact The importance of avoiding rupture or failue of the diaphragm 26 places a premium on eliminating failure producing stresses on the diaphragm, particularly in thepumping of fluids under high pressure.

The diaphragm 26 is actuated by thecyclic application of hydraulic pressure to the diaphragm in'opposition to the pressure-on, the diaphragm of the fluid being pumped. Thus, the diaphragm is actuated bya quantity. of hydraulic fluid contained within an enclosed pumpactuating space which includes the actuating, chamber 42 and a plenum space 54, FIG. 2, which receives the inner end of the reciprocable plunger 18. The plenum space 54,is formed in; part by a space within the. previously mentioned bore 22. The bore 22 is concentric with the diaphragm 26 and merges with a counterboreSG which extends from thebottomof tl1e,cavi ty,38;toward the plunger 18 through a major portion of the body'section-3il. The counterbore 56 provides spacefor receiving the plunger 18, when the latter isfully advanced, together with additional; space for accommodatingdiaphragm biasing structure to be described.

The plenum space 54, communicates, freely. with the actuating chamber 42. Advancement of the plunger '18 forces fluid from the plenum spacefift into the actuating chamber 42, creating hydrostatic pressure on the diaphragm 26 which forces the diaphragm to the left with respecttoFIG. 2,, to expel-fluid from the pumping chamber 40.

Retractionof the plunger l 'iremovesthe plunger from avolume of the plenum space 54 equal to-the displacel m Ofthe. plunger, This would, 'offitself, create a reduced; pressure condition-withinithe pumping space which would cause movement of 'the diaphragm 26 in an intake direction to eflect a corresponding expansionof the pumping chamber 40, provided the-actuating space is completely filled with an optimum volume of hydraulic fluid whichdoes not change during operationof the pump.

However, severe problems canarise during operation of the pump, due to difliculties involved-in maintaining an optimum quantity of hydraulic fluid in the hydraulic actuating space, which is designated" generally in FIG. 2 by the number 58. In the first place, it is impossible as a practical matter to prevent leakage of hydraulic fluidfrorn the actuatingspaceSS past the movable plunger 18. Such leakageof actuating fluid can produce an out of phase relationship of the diaphragm movement to the plunger movement.

When an optimum volume of hydraulic fluid is present in the actuating space 58, advancement of the plunger 18 toits innermost positiondisplaces the diaphragm 26 to its extreme discharge position. In the event the volume of hydraulic fluid in the actuating space 58' has been diminished by leakage, the diaphragm 26 does not move fully through its normal excursion inits discharge direc tion upon movement of the plunger 18 'to its innermost position. The result is a diminution in the active displacement of the diaphragm 26 with a corresponding loss of pumping capacity. i

As a practical matter, it is necessary to provide some means for supplying make-up fluid to the actuating space 58 to compensate for fluid lost from this space. Because of the cyclic lowering of; pressure in theactuating space 58, there is often a tendency foranv excess volume of fluid to fill up in the actuating. space 53 through any means used to add make-up fluid to this space.

The effect of excessfluid in the space 53 is to reduce the intake excursion of the diaphragm 26, with a consequent diminution in pumping eificiency, and to apply excessive-stress tothe diaphragmwhen the plunger 18 moves to its innermost position.

Thus, in order toobtain maximum pumping efliciency, it is necessary that the diaphragm 26 move in phase with the reciprocating motion of the plunger 18 through the normal excursion of the diaphragm. between normal limits of the diaphragm motion. It will be appreciated from the above that this ideal phase relationship of the diaphragm motion to the plunger motion. can be disturbed 'by either an increase or a decrease in the volume of fluid in the space 58. Moreover, the problem of compensating for losses of fluid from the space 5 8, whileat the same time avoiding a, build. up of excess fluid inthis space, becomes more complicated as the cyclic speed of the plunger 18 is'increased. This. stemsfrom the fact that increases in the operating speed of the pump have previously been accompanied by increases. in the degree to which the pressure in the hydraulic actuating space has been reduced on an intake stroke. This isparticularlyv true whenpressure reductions inthe hydraulic actuating space have been relied on to effect movement of the pumping diaphragm in an intake direction. To increase the speed of'the diaphragm, ithas been necessary to increase the pressure reduction inthehydraulic actuating space, as intimated.

Lossesin pumping efliciency and-other: difliculties can arise. due to-the presence ofv entrapped air in the hydraulic actuating space within a pump. ofthischaracter. The compressibility of theair has the eflect of reducing the excursionof the diaphragm.

Such ditflculties associated with the construction and operation of prior diaphragm pumps of thischaracter are eliminated in the improved pump 10 provided by this invention. Moreover, maximum operating eiflciency of the improved pump, even at very high operating speeds, is, assured by, the. operationofextremely simple and inherently reliable pump structure which functions. as an incident to energization of the pump to provide and maintain an optimum volume of hydraulic actuating fluid in --the.actuating space 58, whileat the sametime making special provision for obviating any lag inthe motion of the diaphragm 26 relative to the reciprocating motion of the plunger '18. As will be described in further detail, the maintenance of, an optimum volume of liquid inthe space 58 is achieved through a functional cooperation of diaphragm biasing and stop means with anextremely simplev air-liquid discriminating check valve to release entrapped air from the space 58 andsupply an optimum quantity of liquid to the space asan incident toenergization of the pump.

Thus, as illustrated in FIG. 2' provision is made for maintaining a positive pressure within the actuating space 58 during an intake stroke of the pump until the diaphragm 26 has been retractedto itsextreme intake position. The diaphragm 26 is moved in its. intake direction not by the force of diflerential fluid pressure on the diaphragm but by the action of a biasing spring 6G,continuously appliedto the central portion of the diaphragm.

Preferably, the central portion or" the diaphragm 26 isclamped between two pressure disks 62, 64, which are attached by, a screw fastener 66 to an adjacent end of a hollow spring support sleeveifi which extends from the disk 64 into the counterbore 56, as shown in FIG. 2:

.bore 56 against axial movement by an expandible snap ring 74 seated in the wall of the counterbore.

Movement of the diaphragm 26 in its intake direction is positively terminated, when the diaphragm reaches its extreme intake position, by abutting engagement of the sleeve flange 70 with the bottom of the counterbore 56.

The force of the spring 6% on the diaphragm 26 operates to maintain a positive pressure on fluid within the actuating space 58 until the sleeve 68 bottoms in the counterbore 56 as recited. Normally, the intake movement of the diaphragm 25 will be positively terminated in this manner simultaneously with movement of the plunger 18 to its fully retracted position. In the event there is a deficiency of liquid in the space 58, the sleeve 68 will bottom in the counterbore 56 before the plunger reaches its fully retracted position. Continued movement of the plunger in an intake direction then causes an immediate reduction in pressure within the space 58, to allow entry of additional liquid into the space through a special air-liquid discriminating checir valve 8% communicating with the upper extremities of the space 58 through passages which provide for free rise up to the valve of any air entrapped in the actuating space.

Preferably, the valve 8th is mounted, as shown, in the housing section St) at the bottom of a reservoir 82 for hydraulic actuating fluid formed in the upper portion of the housing 12. The valve 89' is covered with hydraulic fluid and opens automatically in response to a drop in the pressure within the space 58 below ambient pressure conditions to admit liquid into the space 58.

After stopping in its fully retracted position, the plunger 18 accelerates from a standing start in an advancing direction which tends to force fluid from the space 58 out through the valve 80. During the period when the plunger 18 is near the retracted end of its stroke, any air in the space 58 rises into underlying relation to the valve 80 through either a vertical internal bore 84 communicating with the counterbore St: or a generally horizontal bore 86 communicating with the upper extremity of the actuating chamber 42.

By virtue of its capacity to discriminate between air and liquid, the valve 88 will remain open during initial advancement of the plunger 18, to allow air to escape from the space 58 while responding to an incipient discharge of liquid through the valve to immediately close and preclude loss of actuating liquid from the space 58.

It should be appreciated, in this connection, that the release of air from the space 58 during advancement of the plunger 18 serves to create reduced pressure conditions in the space 58 during the subsequent retraction of the plunger 18, with the result that the displaced air is replaced with liquid from the reservoir 82.

The construction of the air-liquid discriminating valve 8t), which enables it to discriminate between air and liquid in allowing the escape of air while precluding the escape of liquid, is illustrated in FIGS. 3 to 7.

As shown in FIG. 3, the valve 80 comprises a small valve cavity 88 of generally cylindrical shape located centrally within a valve housing 98. Preferably, the valve housing 90 is formed by a cylindrical plug element 92 threaded into a downwardly open central bore 9 4 in a bushing element 96, which is removably threaded into the upper end of the housing bore 84-. A cylindrical well 9 8 in the upper end of the plug element 92 coacts with the flat bottom 100 of the bushing bore 94 to define the valve cavity 88.

This cavity encases and provides limited clearance around a short, generally cylindrical valve closure element 102.

The valve closure element 182 is dimensioned diametrically to provide limited radial clearance 104 between the periphery of the valve element and the cylindrical wall of the cavity 88. This provides a restricted flow passage extending axially past the valve element 102 to connect the bottom of the cavity 88 with the top of the cavity. A small axial bore 186 is formed in the plug element 92 in concentric relation to the cavity 88 to connect the actuating space 58 with the bottom of the cavity 88 below the valve element 182. The reservoir 82 communicates with the valve cavity 88 through an outer bore 108 formed in the valve housing element 86 in coaxial relation to the inner bore 186 and opening into the top of the cavity 88.

An upwardly extending stem, tang or pintle 110 centrally formed on the upper side of the valve element 102 projects a substantial distance upwardly into the outer bore 108. The stem or tang 110 is flattened on three longitudinal sides, as shown in FIG. 6, to have a triangular shape in transverse section and to provide three restricted fluid flow passages 112 extending through the bore 1108 alongside the stem.

The valve element 18-2 has an axial length somewhat shorter than the axial length of the cavity 88, thus providing for limited axial movement of the element 102 between an upper, valve closed position, shown in FIG. 4, and a lower, valve open position, shown in FIG. 3. The flat bottom surface 1% of the bore 96 forms a valve seat encircling the bore 108, which is engaged by an O-rin-g seal 114, carried on the upper side of the valve element 102, to close the valve against the escape of fluid from the space 58 upon movement of the valve element 102 against the force of gravity to its upper position.

A transverse kerf or slot 116 cut into the lower 'face of the valve element 192 extends across the adjacent end of the inner valve bore 1% to connect the bore 106 with the restricted cylindrical passage 104 around the valve element 1tl2 when the latter is in its lower, open valve position, shown in FIG. 3.

Upon lowering of the pressure within the actuating space 58 below ambient pressure conditions, due to a deficiency of fluid within the space 58, a differential pressure force is applied to the valve element 107. which is supplemented by the force of gravity on the valve element to cause it to move downwardly to its open position. A quantity of liquid flows through the passages 112 along side the stem 119, through the flow passage 104 around the valve element and through the slot 116 and inner bore 106 into the space 58.

In the event air is entrapped in the space 53, the air rises through the bore 106 and upon advancement of the plunger 18 from a standing start flows around the valve element 182 and out through the restricted passages 112.

The movable valve element 182 is rather light in weight and will respond to a rather small upward force to rise to its closed position.

However, the valve element 102 will remain in its open position to allow a substantial quantity of air to escape during initial advancement of the plunger 18. Because of its compressibility, and because of its very low viscosity and its inherently low fluid friction upon motion, air can flow at a substantial rate through the restricted pass-ages around the valve element 162 without forcing the valve element into its closed position. Thus, the valve 88 permits a substantial quantity of air to escape from the space 58 during each successive advancing stroke of the plunger 18 until the space is completely purged of air.

At the same time, the valve 80 is sensitive to an incipient outflow of liquid through the valve to eflect an immediate closure of the valve, which prevents loss of liquid from the space 58. in contrast to the physical characteristics of air, liquid is not only virtually incompressible, but it has a very high viscosity and a very high fluid friction upon flowing as compared to air. Hence, an incipient outflow of liquid out through the inner bore 106 sprains brings this relatively viscous fluid intoengagement with the under side of the-valve-eleinent 12% This impingement of the liquid on the valve element, together with the frictionaldrag on the valve element of liquid beginningto flow through the restrict-ed passage 184 around the valveelementandthrough the restricted passages 112 alongside the stem 110 snaps the valve element 102mm its closed position.

While the air-liquid discriminating valve 89 operates to admit only an optimum volume of liquid into the space 58, provision is made for-releasing any excess liquid which may for any reason have become entrapped in the space 58,

Anexcessof liquid in the space 58:will causethe diaphragmsupport disk 62 to bottom against the floor of the housingrecess 36. The disk 62 substantially covers the bore44 and'serves, in conjunction-with the curved peripheral edge 12% of the recess 36, to provide strong support tothe-"diaphragm, seeFIG. 8. During continued advancing movement of -;the plunger 18, excess liquid is released fromthe space 53- by opening of a pressure release valve 122 connectedbetween the counterbore 56 and the reservoir 82-,as shown in FIG. 2.

In general, the pressure relief valve l22comprises a compression-springl24 housed within a sleeve 126 to urge a pointed plug 128 against aseat lfiti. Fluid escaping past the plug 12% is discharged'into' the reservoir 82 through a port-132 in the sleeve 126.

The -level=of;hydraulic liquid in the reservoir 82 can he observed ina transparentfiller-stem134- connected vvith the reservoir 82wbelow the normal level of liquid in the reservoir.

IlZWill be appreciated that the invention is not neces sarily limited to the illustratedembod-iment, but includes variants and'al-ternatives withinth-e spirit and scopeof the invention expressed in the claims.

The invention is claimed as follows:

1. A hydraulically actuated diaphragm pump comprising, in combination, housing means defining-apressure cavity, a'diaphragmextending across said cavitytoform a flexible partition separating thecavity into a pumping chamber and a hydraulic actuating chamber, a pump intake spring connected to act on said diaphragm to urge the latter in a direction to expand said pumping chamber and contractsaid actuating chamber, positive stop means coacting with said diaphragm to positively limit motion thereof in pump chamber contracting and expanding directions, meansdefining .anenclosed plenum space communicating with said actuating chamber and forming therewith a pump actuating space, a reciprocable displacementelemen-t movablewithin said plenum space to effect alterntae contraction and expansion thereof, a pressure relief valve communicating with said pump actua'ting spaceto relieve-excess pressure therein, a gas-liquid discriminating check valve including, means. defininga valve cavity locatedabove said actuatingspace, means defining an inner valve passage having an inner. end opening into the. uppermost portion. of said hydraulic actuating, space and-havinganouter. and opening 'into the bottom of said valvecavity, said inner valve passage being positioned so-thattheelevation of every portion thereof is at leastiequal to that of said inner end thereof, means defining an outer valve passage opening into the top of said .valvecavity, a liquid reservoir extending above said check-valve and being connected to said outer valve passagefor continuously. supplying liquidzthereto; said check valve including a check valve disc movab'ly dis? posed int-said valve'cavity. and :biased by gravity .to move between anmupper, valve closed position in which the valve discscloses said outer passageagainst'the outflow of fluid therethroughanda lower, valve .open position; saiddisc being slotted on the underside thereof and being dimensioned inrelation to said; cavity to provide when the disc is in thelower position thereof passage space around the valve disc for the inflowof fluid from said outer passage into said hydraulic actuating space, a valve actuating tang on said valve discextending into one of said passages for both the upper and lower positions of the valve disc, and said tang being'dirnensioned in transverse section to provide limited'pass'ageway space extending through said one passage past said tang for allowing either the inflow of liquid through said check valve into said actuating space or theescape ofgas from said actuating space through said check valve when said disc is in its lower position and to respond to an incipient outflow of liquid from said actuating space through said check valve to move-said valve-disc tosaidupper position thereof.

2. A hydraulically actuated-diaphragm pump comprising, in combination, housing means defining a pressure cavity, a pumping diaphragmextendingacross said cavity to form a flexible partition separating the cavity-into a pumping chamber and a hydraulic actuatingchamber, ineans defining an enclosed plenum space communicating with said actuating chamber and forming-therewith a pump actuatingspace, a'displacementelement coacting with said plenum spaceto effect-alternate contraction and expansion thereof, ages-liquid discriminating check valve including means defining a valve cavity located above said actuatingtspace, means defining an inner valve passage having an-inner end opening into the -uppermost portion of said hydraulic actuating space and having an outer end opening into'saidvalvecavity, said inner valve passage being positioned so that the elevation: of every portion of the inner valvepassage is at least equalto that of said inner end of theinner valve passage, means-defining an outer valve passage opening into said valve cavity, a liquid reservoir extending above'saidcheck valve and being connected tosaid outer valve passage for continuously supplying liquid to said outer -valve passage, said check valve including a check valve element movably disposed-in said'valve-cavity and'biased to-move from a valve closed positionin which the valve element closes said outerpassage against'the outflow of fluid therethrough to an open position; said check valve elementand said valve cavity defining meansbeing shaped and dimensioned in relation to each other to define, when the check valve element is inthe o'pen-positionthereof, an intermediate passage space connecting said.outer-valve passage with said innervalve passage to provide forthe inflow of fluid from said outer passage into 'said hydraulic actuating space; a valve actuating tang on-said valve element extending into 'oneof said'inner andouter valve passages for both the open and closed positions of the valve elements, and said tangbeing-dimensioned in transverse section to provide limited-passageway space extending through said'one valve-passage past said tang when said valve element is in the open positon thereof to provide for both the intake of liquid into said by draulic actuating space through said valve and the escape of gas from said hydraulic actuating space through said valve when the latter isopen and to respond toan incipient outflow of liquid from-said hydraulic actuating space through said valve tomove said valve-element to the closed position thereof.

References Cited in the file-ofthis patent UNITED STATES PATENTS 1,650,377 Nixon Nov. 22, 1927 2,902,044 S-herer et al. Sept. 1, 1959 2,953,096 Sampietro Sept.20, 1960 2,975,599 Bennett Mar, 21, 1961 FOREIGN PATENTS 1,057,878 Germany May 21, ,1959 

1. A HYDRAULICALLY ACTUATED DIAPHRAGM PUMP COMPRISING, IN COMBINATION, HOUSING MEANS DEFINING A PRESSURE CAVITY, A DIAPHRAGM EXTENDING ACROSS SAID CAVITY TO FORM A FLEXIBLE PARTITION SEPARATING THE CAVITY INTO A PUMPING CHAMBER AND A HYDRAULIC ACTUATING CHAMBER, A PUMP INTAKE SPRING CONNECTED TO ACT ON SAID DIAPHRAGM TO URGE THE LATTER IN A DIRECTION TO EXPAND SAID PUMPING CHAMBER AND CONTRACT SAID ACTUATING CHAMBER, POSITIVE STOP MEANS COACTING WITH SAID DIAPHRAGM TO POSITIVELY LIMIT MOTION THEREOF IN PUMP CHAMBER CONTRACTING AND EXPANDING DIRECTIONS, MEANS DEFINING AN ENCLOSED PLENUM SPACE COMMUNICATING WITH SAID ACTUATING CHAMBER AND FORMING THEREWITH A PUMP ACTUATING SPACE, A RECIPROCABLE DISPLACEMENT ELEMENT MOVABLE WITHIN SAID PLENUM SPACE TO EFFECT ALTERNATE CONTRACTION AND EXPANSION THEREOF, A PRESSURE RELIEF VALVE COMMUNICATING WITH SAID PUMP ACTUATING SPACE TO RELIEVE EXCESS PRESSURE THEREIN, A GAS-LIQUID DISCRIMINATING CHECK VALVE INCLUDING MEANS DEFINING A VALVE CAVITY LOCATED ABOVE SAID ACTUATING SPACE, MEANS DEFINING AN INNER VALVE PASSAGE HAVING AN INNER END OPENING INTO THE UPPERMOST PORTION OF SAID HYDRAULIC ACTUATING SPACE AND HAVING AN OUTER END OPENING INTO THE BOTTOM OF SAID VALVE CAVITY, SAID INNER VALVE PASSAGE BEING POSITIONED SO THAT THE ELEVATION OF EVERY PORTION THEREOF IS AT LEAST EQUAL TO THAT OF SAID INNER END THEREOF, MEANS DEFINING AN OUTER VALVE PASSAGE OPENING INTO THE TOP OF SAID VALVE CAVITY, A LIQUID RESERVOIR EXTENDING ABOVE SAID CHECK VALVE AND BEING CONNECTED TO SAID OUTER VALVE PASSAGE FOR CONTINUOUSLY SUPPLYING LIQUID THERETO; SAID CHECK VALVE INCLUDING A CHECK VALVE DISC MOVABLY DISPOSED IN SAID VALVE CAVITY AND BIASED BY GRAVITY TO MOVE BETWEEN AN UPPER, VALVE CLOSED POSITION IN WHICH THE VALVE DISCS CLOSES SAID OUTER PASSAGE AGAINST THE OUTFLOW OF FLUID THERETHROUGH AND A LOWER, VALVE OPEN POSITION; SAID DISC BEING SLOTTED ON THE UNDERSIDE THEREOF AND BEING DIMENSIONED IN RELATION TO SAID CAVITY TO PROVIDE WHEN THE DISC IS IN THE LOWER POSITION THEREOF PASSAGE SPACE AROUND THE VALVE DISC FOR THE INFLOW OF FLUID FROM SAID OUTER PASSAGE INTO SAID HYDRAULIC ACTUATING SPACE, A VALVE ACTUATING TANG ON SAID VALVE DISC EXTENDING INTO ONE OF SAID PASSAGES FOR BOTH THE UPPER AND LOWER POSITIONS OF THE VALVE DISC, AND SAID TANG BEING DIMENSIONED IN TRANSVERSE SECTION TO PROVIDE LIMITED PASSAGEWAY SPACE EXTENDING THROUGH SAID ONE PASSAGE PAST SAID TANG FOR ALLOWING EITHER THE INFLOW OF LIQUID THROUGH SAID CHECK VALVE INTO SAID ACTUATING SPACE OR THE ESCAPE OF GAS FROM SAID ACTUATING SPACE THROUGH SAID CHECK VALVE WHEN SAID DISC IS IN ITS LOWER POSITION AND TO RESPOND TO AN INCIPIENT OUTFLOW OF LIQUID FROM SAID ACTUATING SPACE THROUGH SAID CHECK VALVE TO MOVE SAID VALVE DISC TO SAID UPPER POSITION THEREOF. 